1 . Field of the Invention
This invention relates generally to a filler for a prosthesis for augmentation and reconstruction of a portion of the body and more particularly to an adjunctive filler material for a fluid-fill breast prosthesis.
2. Prior Art
There have been many attempts to improve the hydraulic and/or anatomical behavior of fluid-filled breast prostheses. With prior art implantable fluid-filled prostheses, particularly saline filled prostheses, a number of problems arise. The prosthesis, which is filled with a fluid having different properties than tissue, must preferably preserve the natural softness and resiliency of the body tissue that is being replaced. The most common type of prosthesis used for this purpose has traditionally consisted of a hollow container or shell made of silicone or polyurethane which is molded to the desired anatomical size and shape. The shell is then filled with a material which can be cured to a gel-like consistency such as silicone gel.
Silicone gels have work well in the past to provide a prosthesis having a shape and hydraulic properties similar to that of normal tissue. Saline filled implants, however, do not have sufficient rigidity to retain a particular shape when the patient hosting the implant changes position. The outer shell of the prosthesis is flexible which permits a change in the shape of the prosthesis under the shifting weight of the saline inside the prosthesis.
Saline, having a density of about 1 gram per ml is denser than breast tissue having a density of around 0.8 grams per ml. A saline-filled prosthesis may produce wrinkles in the upper portion and tends to bulge excessively at the lower portion when the wearer stands or leans forward even though the prosthesis is properly shaped when implanted (i.e., when the patient is lying down). Moreover, when the patient is in motion, the hydraulic difference between saline and breast tissue produces a sloshing or gurgling sound within the prosthesis which is esthetically unpleasing.
To overcome these and other problems, various solutions have been attempted. Particular reference is made to U.S. Pat. No. 4,650,487 to Chaglassian, U.S. Pat. No. 4,790, 848 to Cronin and, most particularly, to U.S. Pat. No. 5,171,269 to Bark. Bark teaches the use of a baffling material comprising a fibrous insoluble material which prevents the saline in a saline filled implant from sloshing. Other such fillers include various baffling systems and/or compositions such as cellulose, hemicellulose chitosan and the like. To date, none of the non-silicone gel type fillers provide an esthetically pleasing match between normal breast tissue and the filler material.